Kalshi Event Contracts and Basis Risk

Been dabbling with Kalshi's event contracts, specifically on some of the political outcome ones. I'm finding it hard to get a handle on how to properly size positions when the underlying event has multiple correlated outcomes, or when the contract payout is dependent on an index that might have some basis risk to what I'm actually trying to predict. For instance, if I'm betting on a specific economic data point hitting a range, but the contract is tied to a different, albeit related, index, how do you factor that potential basis difference into your risk sizing? Is it purely a probability adjustment, or do you treat it as a separate, quantifiable risk factor in the Kelly Criterion or whatever method you use?